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What is the cloud?

Before The Cloud

Before The Cloud if you needed a server you had to buy it, install it, run and maintain it, and replace/upgrade it as it became old or failed to meet additional workloads. This would usually require an in-house IT team to look after your sever room. The same goes for Networking, Databases, User management, etc.

This was also inflexible, peak loads at certain time of the year meant that you either had to over-provision for the remainder of the year, or you could not meet demand during peaks and risked site instability and turning users away.

Either way you lose money.

This is one of the (major) scenarios a cloud infrastructure aims to solve.

The Cloud

So what is the cloud:

The Cloud is simply Compute, Network, Storage and other services managed by someone else.

It consists of data centres with cloud services managed by somebody else that are made publicly accessible.

The cloud services cover many different services, e.g. AI, IOT, Kubernetes, etc.

The user pays only for what they use and when they need to use it. It is maintained, patched, secured and monitored by the cloud provider.

The formal definition of the cloud consists of 5 characteristics:

  • On-Demand Self Service
  • Broad Network Access
  • Resource Pooling
  • Rapid Elasticity
  • Measured Service

On-Demand Self Service

No human interaction is required for resource provisioning, i.e. a resource can be provisioned witgh the clisk of a button - no human interaction is required by the provider.

Broad Network Access

Resources I create can be accessed from anywhere via the network. No physical access is required at any time (for example to a physical host machine).

Resource Pooling

Physical resources are shared between customers, and customers will not have any access to another customer's resources or who those customers are.

Some advanced services allow for physical resource separation (so not shared, but therefore more expensive)

Rapid Elasticity

Resources can be scaled up and down automatically as needed. No need to purchase resources for a one-time peak scenario.

Measured Service

You only pay for the resources actually used, when used, e.g. Server time, DB Storage, Function calls, etc. measured by the second. No need to invest money into non-used resources.

CapEx vs OpEx

Capital Expenditure is reduced, we no longer have to purchase hardware up front, along with the operating expenditure of keepin those systems running. With the cloud it moved to operating expenditure, we pay only for what we actually use and this is itself more flexible as we only pay for what we use. This is more financially efficient.

Types of Cloud Services

IaaS - Infrastructure as a Service

The cloud provides the underlying platform:

  • Compute
  • Networking
  • Storage

The client handles and is responsible for everything else. The cloud provides the minimal infrastructure. Typically this is the scenario of using virtual machines onto which the client loads and configures the software and services required.

PaaS - Platform as a Service

The cloud provides the platform for running apps such as:

  • Compute
  • Networking
  • Storage
  • Runtime Environment
  • Scaling
  • Redundancy
  • Security
  • Updates & Patching
  • Maintenance
  • Etc.

The client just supplies the code to run, the most common example is for Web Apps.

The client has *no access to the underlying virtual machines. The cloud provider is responsible for ensuring the environment is operational.

SaaS - Software as a Service

A software running completely in the cloud. The client does not need to install anything, common examples being Office365 or Salesforce. We essentially become the end user.

Cloud Service Responsibilities

Additional Service Types

  • FaaS - Functions as a Service
  • DBaaS - Database as a Service
  • DaaS - Desktop as a Service
  • IOTaaS - IOT as a Service
  • AIaaS - AI as a Service

Types of Cloud

There are three types of cloud:

Public Cloud

  • Set up in the public network
  • Managed by large companies (Microsoft, Amazon, Google, etc.)
  • Accessible via the internet
  • Available to all clients and users
  • Clients have *no access to the underlying infrastructure.

Examples are AWS, Azure, Google Cloud, etc.

Private Cloud

  • A cloud set up in an organisation's premises.
  • Managed by the organisation's IT team.
  • Accessible only within the organisation's network.
  • Available only to users in that organisation.
  • Uses private cloud infrastructure and engines.
  • Contains only a subset of public cloud capabilities .
  • Used for security purposes.

Examples are VMWare Cloud, Red Hat Open Shift, Azure Stack.

Hybrid Cloud

  • A cloud set up in an organisation's premises...
  • ...but also connected to the public cloud.
  • Workload can be separated between the two clouds.
  • Sensitive data can be located in the organisation's premises, public data in the public cloud.
  • Usually (but not always) managed by the public cloud, but can be the opposite way around.

Examples are Azure Arc, or AWS Outposts.